The present disclosure is generally related to a rubber composition. More particularly, the present disclosure is related to a rubber composition comprising a silica filler, and a N-substituted polyalkylene succinimide derivative. The addition of the N-substituted polyalkylene succinimide derivative allows for a reduction in the amount of processing oil required in the rubber composition. The composition is useful in manufacturing rubber articles such as tires with reduced rolling resistance, improved wet/snow traction and winter softness, improved dynamic stiffness, improved tensile strength, easy handling, and/or compatibility with higher environmental standard, among others.
Various imide compounds have been used in rubber compounding. For example, U.S. Pat. No. 4,322,336 to Machurat et al. teaches that a minor amount of an alkenyl succinimide may be incorporated into a filled/plasticized natural or synthetic rubber, to enhance the compatibility between reinforcing filler such as silica and plasticizer such as oil. The alkenyl succinimides were prepared by reacting anhydrides such as tetrapropenyl succinic anhydride and polyisobutenyl succinic anhydride with amines including tris(3-oxa-6-aminohexyl)amine, 1-10-diamino-4,7-dioxadecane, ethylene diamine, para diamino benzene, bis-hexamethylene triamine, and tetraethylene pentamine.
U.S. Pat. No. 3,944,552 to Lawrence discloses some imide compounds in rubber composition such as N-(morpholinothio)-succinimide, N-(piperidinothio)-succinimide, N-(morpholinothio)-maleimide, N-(dibenzylaminothio)-maleimide, N-(morpholinothio)-glutarimide, and N-(2,6-dimethylmorpholinothio)-glutarimide. The imide compounds are used as sulfur donors to increase the state of vulcanization or to permit the use of lesser amounts of free sulfur.
U.S. Pat. No. 5,922,792 to Wideman et al. discloses a rubber composition comprising from 0.1 to 10 phr of a sulfur containing bis-succinimide of the formula:
wherein R is selected from the group consisting of hydrogen and alkyls having from 1 to 18 carbon atoms and x is an integer of from 1 to 8. In exemplified embodiments, tetrathiodisuccinimide was prepared from the reaction between N-chlorosuccinimide and red-colored tetrasulfide dianion, which was formed by mixing sodium sulfide nonahydrate and sulfur in distilled water at elevated temperature. The use of sulfur containing bis-succinimide with a silica coupler resulted in higher modulus, E′ (stiffness), hardness properties (at room temperature) and rebound values.
U.S. Pat. Nos. 5,981,662 and 6,174,989, both to D'Sidocky et al., disclose some rubber compounds containing polymeric bis-succinimide polysulfides such as poly N,N′-m-Xylylenebis(3-methylsuccimimide)polysulfide. Rubber compounding results showed improvements in retention of modulus during overcure and with increasing cure temperature, improvements in retention of tensile strength, improvements in retention of hardness and improvements in retention of rebound properties.
U.S. Pat. No. 6,632,781 to Harrison et al. discloses a lubricant composition comprising an alkali metal borate dispersed in a polyalkylene succinic anhydride and a metal salt of a polyisobutenyl sulfonate. The polyalkylene succinic anhydride is selected from polyalkylene succinic anhydride, non-nitrogen containing derivatives of polyalkylene succinic anhydride, and mixtures thereof. The lubricant composition is described as useful in high load conditions such as occur in the gears of automobile transmission and differentials.
U.S. Pat. No. 5,393,309 to Cherpeck discloses the use of a polyisobutenyl succinimide derivative in combination with a nonvolatile paraffinic or naphthenic carrier oil as a fuel additive. The derivative is prepared by reacting ethylenediamine or diethylenetriamine with a polyisobutenyl succinic anhydride.
The technology described herein provides a new class of N-substituted polyalkylene succinimide derivative used together with silica filler in rubber compositions. Rubber articles such as tires made from such composition can exhibit unexpected properties such as reduced rolling resistance, improved wet/snow traction and winter softness, improved dynamic stiffness, improved tensile strength, easy handling, and/or compatibility with higher environmental standard, among others.